2.3L ('83-'97) Searching for idle at cold start, running rich

[Jamie Reid]

I am a new member here owning a 1988 ranger XLT 2.3 Manuel transmission and have used these forums and discussions to help diagnose issues I’ve had in the past for quite some time. I really appreciate this platform and the wealth of knowledge here, so anything I gain from here is a win and if this thread can help others out in the future, that’s even better.
The symptoms for the problem I am having include rough idle at cold start until the system adjusts for idle, runs rich and lacks power, intermittent sputter or misfire on occasion.

I believe I’ve narrowed this down to either my iac valve, (which is not a motorcraft part) or a problem with the ect sensor.

After testing the ect sensor in a pot of water, it seems to be operating correctly. However when I test for basic continuity to the sensor, I get nothing. That doesn’t seem normal to me.
The harness for the ect sensor seems to be in good shape. When I back probe the signal and ground wires individually I am getting 12 v at ground and 3.45 at signal. Signal seems a bit low.. but there’s voltage coming from signal wire with KOEO.

from what I can tell the iac is functioning and serves its purpose, however since it is not a motor craft part, my worry is that it is not communicating with the ecm properly and contributing to my issue.

 

[Chapap]

The symptoms for the problem I am having include rough idle at cold start until the system adjusts for idle, runs rich and lacks power, intermittent sputter or misfire on occasion.

welcome!

are all the symptoms happening when cold, or only the rough idle?

 

[Jamie Reid]

When I start the engine it idles poorly for about a minute then it smooths out and gets better, it will do this if the engine is hot or cold and runs rich all the time

 

[RonD]

ECT sensor is a 5volt sensor, like all the other sensors

Sensors all share a common 5v wire from the computer's 5v power supply, then have a return wire to the computer that is a lower voltage, the sensors Feedback voltage

So ECT should have 5v IN and then 3v out if cold, 70deg
At operating temp, 180deg, should see under 1volt out

 

[Jamie Reid]

Testing the sensor shows this. Looks like it I operating corectly.

 

[Chapap]

There’s a very long list of things that’ll make it run rich. I’m down to the crank sensor on mine.

I have a shot in the dark for rough idle tho. Since engine temp doesn’t matter and it’s always for the first min or so, could there be a leak in a gas line? Air gets in and it idles rough till all the air is purged? First guess is IAC, but I wouldn’t think it’d fix itself every time.

 

[Jamie Reid]

There's always an intermittent miss when traveling and a lot of the time in first gear. The filter, pump, and FPR are all new, and I see what you are saying. I triple checked all the line and injectors to make sure there's no leaks.
I'm sure several other folks can understand when I say this has been the most frustrating thing ever.

 

[Chapap]

There's always an intermittent miss when traveling and a lot of the time in first gear. The filter, pump, and FPR are all new, and I see what you are saying. I triple checked all the line and injectors to make sure there's no leaks.
I'm sure several other folks can understand when I say this has been the most frustrating thing ever.

I got great improvement after changing the ICM. Everything was bad on my truck including ECU. I should have my crank sensor changed this weekend. I’m running pig rich and have misses. The crank sensor is literally the last electrical thing to change. Try running the truck on each coil pack alone and see if they both behave the same. If so, I think that points towards ICM.

 

[Jamie Reid]

Hello again everyone.
I’m still struggling with this and would like to ask a question, along with a recap of what symptoms are still present and the what I’ve done in an attempt to fix the issues.

The engine starts with a rough/chugging idle and levels out after a minute or 2. Sometimes, when put slightly under load in first gear, the engine will stall, and/or will bog out, even with WOT. Other times it will run and drive with poor power for a short distance before it ultimately starts spitting and sputtering until a stall. The engine runs very rich.

I have replaced the timing belt and distributor, while setting the spout connector. Replaced injectors, fuel pump and filter, Fule pressure regulator, pressure and temp sensors, air idle control, map, ecm, pcv, egr, o2 sensor, ALL ignition components, I’ve taken apart the intake manifold for a gentle but proper cleaning and reassembly including throttle body and calibrated the TPS voltage, no vacuum leaks, no collapsed hoses. All cylinders have good compression. (THE ONLY thing I have not put my hands on is the sending unit in the tank, however, the fule guage works and I’m getting good fule pressure, according to guage tests.)

It seems like the walker productsTPS replacements I purchased have make no difference, because the range of voltage continues to be lost shortly after calibration and test drives, I’ve replaced the plug assembly for the tps and it still happens. Maybe a short in the harness?

My main question is this- what is the likleyhood of the throttle body itself failing and needing to be replaced all together? Is there a proper way to diagnose? Am I missing something?

 

[RonD]

Gas engines need compression, spark and fuel

If compression is equal in all 4 cylinders then that can be taken off the table, compression doesn't tend to be variable
Leaving spark and fuel, which can be variable, lol

1988 2.3l will use a distributor for spark
Check its shaft for wobble, not an uncommon issue on older distributors, even ones with short shafts like the 2.3l
The distributor drive gears on these were also an issue

Computer runs the fuel system
If its running Rich after warm up then computer is getting bad info from one or more sensors or computer itself is bad
If you can read the codes then do a "sanity test" on computer, new or not
Unplug 1 sensor like ECT temp sensor
Start engine
CEL(check engine light) should come on right away
Shut off engine and check the codes
Then try another sensor, like the TPS
Point of the tests is to see if computer is monitoring systems like it should

Rich issue could be old injectors leaking but that's not just Rich running, thats smoke out the tail pipe RICH running, lol

Pull out the 4 spark plugs and have a look at the tips, darkish Brown means Rich running
Blackish color is oil burning so valve guide seals, if compression was above 145psi or so
Spark plugs don't spark well with oil in the cylinders

 

[Chapap]

I have a similar problem with my 94 Lima (coil packs, not distributor). I've replaced everything like you (including computer) and still run rich. I do perfectly fine when cold and it gets rough when hot. I've kinda given up since it seems to run fine. It still bothers me that I can't figure it out

 

[Bosshawg1178]

I am a new member here owning a 1988 ranger XLT 2.3 Manuel transmission and have used these forums and discussions to help diagnose issues I’ve had in the past for quite some time. I really appreciate this platform and the wealth of knowledge here, so anything I gain from here is a win and if this thread can help others out in the future, that’s even better.
The symptoms for the problem I am having include rough idle at cold start until the system adjusts for idle, runs rich and lacks power, intermittent sputter or misfire on occasion.

I believe I’ve narrowed this down to either my iac valve, (which is not a motorcraft part) or a problem with the ect sensor.

After testing the ect sensor in a pot of water, it seems to be operating correctly. However when I test for basic continuity to the sensor, I get nothing. That doesn’t seem normal to me.
The harness for the ect sensor seems to be in good shape. When I back probe the signal and ground wires individually I am getting 12 v at ground and 3.45 at signal. Signal seems a bit low.. but there’s voltage coming from signal wire with KOEO.

from what I can tell the iac is functioning and serves its purpose, however since it is not a motor craft part, my worry is that it is not communicating with the ecm properly and contributing to my issue.

Check your DPFE Sensor. It's easy to check even if you don't have a scanner or scanner doesn't support DPFE..
Sensor is located on passenger side towards the back. It has 2 hoses (approx 1/2" diameter.) Coming from the bottom of it. Look up Eric the Car guy on YouTube... If that's not it, then more than likely... RECESSED VALVE SEATS... Check out this video.